Thread: Alternator / Voltage Regulator
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Old 09-12-2015, 02:45 PM
strictlypersonl strictlypersonl is offline
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Originally Posted by Large Arbor View Post
Hey Patrick and others,

New battery, new VR, and New Alternator and the battery is not staying charged. It was tested last week and had 800 plus cranking amps. I ran the car for 20 minutes and the battery is now reading about 9 volts with a charger on it. I took a voltage reading from the alternator when running and it read 18 V.

The only thing known drawing current is the fan. How do I diagnose this problem? Could I still have a bad VR?

Phil
You should see a maximum of about 14.7V when charging a fully-charged battery. More than that and there's a problem in the voltage regulator, its circuit connections and/or its ground.
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